We often get questions about stroke.  The fly in the ointment is that term 'stroke' is ambiguous, mistaking one for the other can have significant consequences.

An easy introduction to the two main types can be found in the patient information leaflet 'What is a stroke' produced by the UK's Stroke Association.

The most common type of stroke is a blockage. This is called an ischaemic stroke, which happens when a clot blocks an artery that carries blood to the brain. It may be caused by:

• A cerebral thrombosis, when a blood clot (thrombus) forms in a main artery to the brain;
• A cerebral embolism, when a blockage caused by a blood clot, air bubble or fat globule (embolism) forms in a blood vessel somewhere else in the body and is carried in the bloodstream to the brain; or
• A blockage in the tiny blood vessels deep within the brain (lacunar stroke).

The second type of stroke is a bleed, when a blood vessel bursts, causing bleeding (haemorrhage) into the brain. This is called a haemorrhagic stroke. It may be caused by:

• An intracerebral haemorrhage, when a blood vessel bursts within the brain; or
• A subarachnoid haemorrhage, when a blood vessel on the surface of the brain bleeds into the area between the brain and the skull (subarachnoid space).

Another related condition is a Transient Ischaemic Attack (TIA), which is frequently referred to as a mini-stroke. Wikipedia reports that a TIA is caused by the temporary disturbance of blood supply to a restricted area of the brain, resulting in brief neurologic dysfunction that usually persists for less than 24 hours.

For more background reading

• Stroke (Wikipedia)
• TIA (Wikipedia)
• Search TRIP for articles on stroke (click here)
• Search TRIP for articles on tia (click here)